The present invention relates, in general, to a brachytherapy seed delivery system and method and, more particularly, to a brachytherapy seed delivery system and method utilizing dimensionally stable spacers between brachytherapy seeds.
Prostatic cancer has been estimated to affect as many as one in three men. In the U.S. alone, this implies an estimated fifty-million patients who are candidates for treatment of prostatic cancer. Prior methods of treatment include surgical intervention, external radiotherapy, and other brachytherapy (interstitial radiation) techniques. A general discussion of the localized use of radiation therapy is found in Bagshaw, M. A., Kaplan, I. D. and Cox, R. C., Radiation Therapy for Localized Disease, CANCER 71: 939-952, 1993. Disadvantages associated with surgical intervention include impotence and incontinence. External radiotherapy may have deleterious effects on surrounding normal tissues (e.g., the bladder, the rectum, and the urethra). In contrast, brachytherapy diminishes complications such as impotence and incontinence, and allows a higher and more concentrated radiation dose to be delivered to the prostate gland as compared to external radiotherapy. An additional advantage of brachytherapy is that treatment can be accomplished within a matter of days as compared to weeks, greatly reducing radiation exposure of the adjacent organs.
Prostate brachytherapy can be divided into two categories, based upon the radiation level used. The first category is temporary implantation, which uses high activity sources, and the second category is permanent implantation, which uses lower activity sources. These two techniques are described in Porter, A. T. and Forman, J. D., Prostate Brachytherapy, CANCER 71: 953-958, 1993. The predominant radioactive sources used in prostate brachytherapy include iodine-125, palladium-103, gold-198, ytterbium-169, and iridium-192. Prostate brachytherapy can also be categorized based upon the method by which the radioactive material is introduced into the prostate. For example, a open or closed procedure can be performed via a suprapubic or a perineal retropubic approach.
Prostate cancer is a common cancer for men. While there are various therapies to treat this condition, one of the more successful approaches is to expose the prostate gland to radiation by implanting radioactive seeds. The seeds are implanted in rows and are carefully spaced to match the specific geometry of the patient""s prostate gland and to assure adequate radiation dosages to the tissue. Current techniques to implant these seeds include loading them one at a time into the cannula of a needle-like insertion device, which may be referred to as a brachytherapy needle. Between each seed may be placed a spacer, which may be made of catgut. In this procedure, a separate brachytherapy needle is loaded for each row of seeds to be implanted. Typically, if a material such as catgut is used as a spacing material the autoclaving process may make the spacer soft and it may not retain its physical characteristics when exposed to autoclaving. It may become soft, change dimensions and becomes difficult to work with, potentially compromising accurate placement of the seeds. Alternatively, the seeds may be loaded into the center of a suture material such as a Coated VICRYL (Polyglactin 910) suture with its core removed. In this procedure, brachytherapy seeds are carefully placed into the empty suture core and loaded into a needle-like delivery device. Although Coated VICRYL suture is able to withstand autoclaving, the nature of its braided construction can make the exact spacing between material less than desirable.
It would, therefore, be advantageous to design a seed delivery system utilizing a plurality of spacers which are absorbable and which do not degrade significantly when subjected to typical autoclave conditions. It would further be advantageous to design a method of loading a brachytherapy seed delivery system utilizing a plurality of spacers which are absorbable and which do not degrade significantly when subjected to typical autoclave conditions. It would further be advantageous to design an improved brachytherapy method utilizing a plurality of spacers which are absorbable and which do not degrade significantly when subjected to typical autoclave conditions.
The present invention is directed to a brachytherapy seed delivery system which includes a seed cartridge including a central channel, a plurality of brachytherapy seeds disposed within the central channel and a plurality of absorbable, dimensionally stable spacers disposed within the central channel, wherein the absorbable, dimensionally stable spacers are interspersed between the brachytherapy seeds. Further embodiments of the present invention include a brachytherapy seed delivery system as described above wherein the spacers are cylindrical in shape, having a diameter of approximately 0.035 inches. Further embodiments of the seed delivery system described above include a brachytherapy seed delivery system wherein the spacer is manufactured from dimensionally stable Polyglactin 910, a dimensionally stable compound of 95% polylactic acid and 5% polyglycolic acid or dimensionally stable polylactic acid.
The present invention is further directed to a method of loading a brachytherapy seed delivery system including the steps of: providing a seed cartridge including a central channel; placing at least two brachytherapy seeds into the central channel of the seed cartridge; placing at least one absorbable, dimensionally stable spacer in the central channel between the brachytherapy seeds; connecting the brachytherapy seed cartridge to a brachytherapy needle including a cannula; and forcing the seeds out of the brachytherapy seed cartridge into the cannula. Further embodiments of the present invention include a method of loading a brachytherapy seed delivery system as described above, wherein the absorbable, dimensionally stable spacer comprises dimensionally stable Polyglactin 910, a dimensionally stable compound of 95% polylactic acid and 5% polyglycolic acid or dimensionally stable polylactic acid.
The present invention is further directed to an improved brachytherapy method including the steps of: providing a seed cartridge including a central channel; placing at least two brachytherapy seeds into the central channel of the seed cartridge; placing at least one absorbable, dimensionally stable spacer in the central channel between the brachytherapy seeds; connecting the brachytherapy seed cartridge to a brachytherapy needle including a cannula; forcing the seeds out of the brachytherapy seed cartridge into the cannula; inserting the brachytherapy needle into a human organ; and forcing the seeds and the spacer through the cannula and into the human organ. Further embodiments of the present invention include an improved brachytherapy method as described above wherein the absorbable, dimensionally stable spacer comprises dimensionally stable Polyglactin 910, a dimensionally stable compound of 95% polylactic acid and 5% polyglycolic acid or dimensionally stable polylactic acid.